Automatic sheet feeder having a flexible element on one end of the pick shaft

ABSTRACT

In an auto sheet feeder, a flexible element is disposed monolithically at one end of a pick shaft, the flexible element capable of moving close to or away from the center of a ratchet. A fluctuation section of the flexible element comprises a pawl for engaging with an inner tooth of the ratchet, allowing the ratchet for one-way rotating the pick shaft. A clutch pushes a pin of the flexible element and disengages the flexible element with the ratchet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

the present invention relates to an automatic sheet feeder, and more specifically, to an automatic sheet feeder having a flexible element on one end of the pick shaft.

2. Description of the Prior Art

Most image processing machines such as copiers, fax machines, printers, scanners, or multifunctional business machines are equipped with an auto sheet feeder (ASF) for feeding recording medium into the main section of the image processing machines. To lower the cost for manufacturing, the driving power generated by a motor for driving the ASF is also utilized to drive the paper conveying device. In the image processing machines the power is transmitted to each operating part through the gear set therein. A prior art ASF can handle one-way paper feeding as the motor drives the gear sets, which then drives a ratchet to rotate, and finally the ratchet, which connects with the pick shaft of the ASF, drives the pick shaft to rotate in one-way direction.

Since the ASF allows the papers to proceed in one direction and when the image processing machine does not feed the papers, the ASF (also known as the driven member) shall not be driven by the driving member (the ratchet and the gear set), the prior art ASF has an O-ring of particular appearance and a clutch member installed on one end of the pick shaft. Please refer to FIG. 1 and FIG. 2. The automatic sheet feeder disclosed in the U.S. Pat. No. 6,899,326 in FIG. 1 and FIG. 2 has an O-ring 140 on the pick shaft 110 for operating with the ratchet 120. The O-ring 140 comprises a pawl 144 and a brake pin 142. The pawl 144 is engaged with the ratchet 120 so that when the ratchet 120 rotates along the direction CW, the ratchet 120 can drive the pick shaft 110 to rotate along the direction CW as well, which is shown in FIG. 1. When the image processing machine does not feed the papers, a clutch in the image processing machine pushes the brake pin 142 in the direction F, making the O-ring 140 to rotate along the direction CCW taking the shaft 146 as the axle, which is shown in FIG. 2. At this time, the pawl 144 disengages with the ratchet 120, the ratchet 120 has an idle running with the pick shaft 110, and the restoring spring 150 connected between the pick shaft 110 and the O-ring 140 is elongated and has a restoring force. When the image processing machine is in the paper feeding procedure again, the clutch stops pushing the brake pin 142 and the restoring force of the restoring spring 150 pulls the O-ring 140 along the direction CW, making the pawl 144 of the O-ring 140 to engage with the ratchet 120 so as to drive the pick shaft 110 to rotate.

However, in the ASF according to the prior art, the aforementioned one-way driving and disengagement are accomplished by the O-ring 140 and the restoring spring 150, the assembly of which is complicated as well: the restoring spring 150 must be installed with one end on the hook of the pick shaft 110 and a rotating axle 146 of the O-ring 140 installed on a rotating pivot of the pick shaft 110. Then a pair of tweezers is necessary for clipping the other end of the restoring spring 150, stretching the restoring spring 150, hooking the other end of the restoring spring 150 on the hook of the O-ring 140. As the O-ring 140 and the restoring spring 150 are kept in the position, the ratchet 120 is assembled then. The process of assembly according to the prior art is very complicated and the assembled elements are very easy to fall apart. Furthermore, the O-ring 140 and the restoring spring 150 raise the cost as well.

SUMMARY OF THE INVENTION

The claimed invention provides an automatic sheet feeder having a flexible element on one end of the pick shaft. The automatic sheet feeder comprises a ratchet having a plurality of teeth and a pick shaft having a flexible element. The flexible element comprises a fixed section extending from the end of the pick shaft and a fluctuation section extending from the fixed section capable of moving close to or away from an axis. The fluctuation section comprises at least a pawl for engaging with the teeth of the ratchet, allowing the ratchet for rotating the pick shaft.

The claimed invention also provides an automatic sheet feeder having a flexible element on one end of the pick shaft. The automatic sheet feeder comprises a ratchet having a plurality of teeth and a pick shaft having a flexible element extending from the end of the pick shaft. The flexible element is capable of moving close to or away from an axis and comprises at least a pawl for engaging with the teeth of the ratchet, allowing the ratchet for rotating the pick shaft.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 and FIG. 2 are illustrations of the O-ring operating with the ratchet in the automatic sheet feeder according to the prior art.

FIG. 3 is an illustration of the automatic sheet feeder according to the present invention.

FIG. 4 is an illustration of the flexible element on one end of the pick shaft.

FIG. 5 is an illustration of the cross section of the flexible element in FIG. 4.

DETAILED DESCRIPTION

Please refer to FIG. 3. FIG. 3 is an illustration of the automatic sheet feeder (ASF) 1 according to the present invention, which can be applied on image processing machines such as copiers, fax machines, printers, scanners, or multifunctional business machines. The ASF 1 comprises a pick shaft 10, a ratchet 20, and a clutch 30. A flexible element 40 is disposed on one end of the pick shaft 10 and on the other end of the pick shaft 10, a pickup roller 11 disposed thereon is wrapped with high frictional rubber and capable of conveying the papers forward when the pick shaft 10 is driven to rotate in one-way direction by the ratchet 20. the ASF 1 according to the present invention works as followed: The motor of the image processing machine drives the gear set (not shown in the Figure) to rotate. The gear set then operates with the outer teeth 26 of the ratchet 20 and therefore drives the ratchet 20 to rotate along the direction CW. The inner teeth 22 of the ratchet 20 (shown in FIG. 5) then operate with the pick shaft 10 and drive the pick shaft 10 to rotate along the direction CW, hence conveying the papers forward.

Please refer to FIG. 4 and FIG. 5. FIG. 4 is an illustration of the flexible element 40 on the first end of the pick shaft 10. FIG. 5 is an illustration of the cross section of the flexible element 40 in FIG. 4. The flexible element 40 comprises a fixed section 41 and a fluctuation section 42 wherein the fixed section 41 extends from the first end of the pick shaft 10 and the fluctuation section 42 is connected with the fixed section 41. Since the fluctuation section 42 extends from the fixed section 41 and hangs on the first end of the pick shaft 10, The fluctuation section 42 is flexible and capable of slightly moving close to or away from an axis, which in the present invention, the fluctuation section 42 is capable of moving close to or away from the axle of the pick shaft 10 and because the ratchet 20 is rotatably disposed on the axle of the pick shaft 10, the fluctuation section 42 substantially “swings” close to or away from the center 24 of the ratchet 20. The flexible element 40 and the pick shaft 10 in the present invention are monolithically made and the flexible element 40 (as well as the first end of the pick shaft 10 or the pick shaft 10 itself) is composed of material with dynamic fatigue-proof, wear-proof, high strength, high toughness such as TPEE or PA66.

In FIG. 5, a pawl 43 is disposed on the fluctuation section 42, extending from one side close to the center 24 of the ratchet 20. The pawl 43 is for engaging with the inner teeth 22 of the ratchet 20 so that the ratchet 20 is capable of driving the pick shaft 10 to rotate when the ratchet 20 rotates along the direction CW. In the present invention, more than one pawl 43 can be disposed on the fluctuation section 42 to engage with a plurality of teeth 22 of the ratchet 20 at the same time to provide the pawls 43 for operating with the ratchet 20 more accurately and for the ratchet 20 to transfer more stable driving torque. The inner tooth 22 has a tooth-like incline 221 that pushes the pawl-like incline 431 of the pawl 43 so that the ratchet 20 can drive the pick shaft 10 to rotate. For the pawl 43 to engage with the inner tooth more easily, the tooth-like incline of the inner teeth 22 and the pawl-like incline of the pawl 43 are designed to have their extension lines passing through the center of the ratchet 20.

In order to lower the cost of the transmission power source and the transmission mechanism in the image processing machine, the ratchet 20 has to be disengaged with the pick shaft 10 when the ASF 1 does not feed the paper. Thus, the ratchet 20 does not drive the pick shaft 10 and cause error when the transmission motor keeps driving the gear set and the ratchet 20 for other movement such as paper conveying process or paper ejection process. Therefore, the ASF 1 further comprises a clutch 30 and the flexible element 40 further comprises a brake pin 44 extending from one end of the fluctuation section 42. Please refer to FIG. 3 and FIG. 5. When the image processing machine does not feed the paper, the gear set makes the clutch 30 to push the brake pin 44 along the direction F in FIG. 5, enabling the fluctuation section 42 and the pawl 43 thereon to swing slightly along the direction CCW relative to the fixed section 41. The slight swing causes the fluctuation section 42 and the pawl 43 thereon to move away from the ratchet 20 and the inner tooth 22 and disengage the pawl 43 with the inner tooth 22 so that the ratchet 20 is idle running corresponding to the pick shaft 10. When the image processing machine starts feeding paper again, the gear set drives the clutch 30 to rotate and the clutch 30 stops pushing the brake pin 44 so that the flexible element 40 restores to its original position, the pawl 43 engaging the inner tooth 22 again and feeding the paper.

In the exemplary embodiment according to the present invention, the curvilinear outline of the flexible element 40 (including the fixed section 41 and the fluctuation section 42) stretches by following close to the periphery of the ratchet 20, which makes the fluctuation section 42 performs only a small swing to disengage with the ratchet 20. On the other hand, the fixed section 41 is not a necessary part in another exemplary embodiment. The flexible element 40 extends directly from the first end of the pick shaft 10 and can swing close to or away from the shaft of the pick shaft 10 (or the center 24 or the ratchet 20).

The present invention utilizes a flexible element disposed monolithically at one end of a pick shaft, capable of moving close to or away from the center of a ratchet to achieve one-way auto sheet feeding in an image processing machine. A fluctuation section of the flexible element comprises a pawl for engaging with an inner tooth of the ratchet, allowing the ratchet for one-way rotating the pick shaft. A clutch pushes a pin of the flexible element and disengages the flexible element with the ratchet, which therefore simplifies the auto sheet feeder in the image processing machine by reducing the additional members like an O-ring and a restoring spring.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

1. An automatic sheet feeder having a flexible element on one end of the pick shaft, comprising: a ratchet having a plurality of teeth; and a pick shaft having a flexible element, the flexible element comprising: a fixed section extending from the end of the pick shaft; and a fluctuation section extending from the fixed section capable of moving close to or away from an axis, the fluctuation section comprising at least a pawl for engaging with the teeth of the ratchet, allowing the ratchet for rotating the pick shaft.
 2. The automatic sheet feeder of claim 1, further comprising a clutch, the flexible element further comprising a brake pin extending from one end of the fluctuation section for operating with the clutch.
 3. The automatic sheet feeder of claim 1 wherein the fluctuation section extends from the fixed section capable of moving close to or away from the center of the ratchet.
 4. The automatic sheet feeder of claim 1 wherein the plurality of teeth of the ratchet comprises a tooth-like incline and the pawl comprises a pawl-like incline, the extension lines of both the tooth-like incline and the pawl-like incline passing through the center of the ratchet.
 5. The automatic sheet feeder of claim 1 wherein the fixed section and the fluctuation section extend from the end of the pick shaft by following the periphery of the ratchet.
 6. An automatic sheet feeder having a flexible element on one end of the pick shaft, comprising: a ratchet having a plurality of teeth; and a pick shaft having a flexible element extending from the end of the pick shaft, the flexible element capable of moving close to or away from an axis and comprising at least a pawl for engaging with the teeth of the ratchet, allowing the ratchet for rotating the pick shaft.
 7. The automatic sheet feeder of claim 6, further comprising a clutch, the flexible element further comprising a brake pin extending from one end of the flexible element for operating with the clutch.
 8. The automatic sheet feeder of claim 6 wherein the flexible element extends from the end of the pick shaft capable of moving close to or away from the center of the ratchet.
 9. The automatic sheet feeder of claim 6 wherein the plurality of teeth of the ratchet comprises a tooth-like incline and the pawl comprises a pawl-like incline, the extension lines of both the tooth-like incline and the pawl-like incline passing through the center of the ratchet.
 10. The automatic sheet feeder of claim 6 wherein the flexible element extends from the end of the pick shaft by following the periphery of the ratchet. 